Tri-Colour Data Packet Counting for Tri-Colour Marking Policies

1. A method of counting packets of a data packet flow marked according to a tri-color marking scheme, comprising the steps of: receiving a packet of the flow; determining whether the flow matches a srTCM flow policy; determining an identifier for the flow; determining a marked color of the received packet; incrementing a first counter at a first ternary content-addressable memory (TCAM) entry corresponding to the identifier responsive to the marked color being a first color of said tri-color marking scheme; incrementing a second counter at the first TCAM entry corresponding to the identifier responsive to the marked color being a second color of said tri-color marking scheme; and incrementing a third counter at a second TCAM entry corresponding to the identifier.

2. The method of claim 1 , further comprising determining a count of packets from the flow having a marked color being a third color of said tri-color marking scheme by subtracting from a current count of the third counter a sum of current counts of the first and second counters.

3. The method of claim 1 , wherein the first and second colors are green and yellow and the third color is red.

4. The method of claim 1 , wherein the first and second counters are implemented on a first TCAM and the third counter is implemented on a second TCAM.

5. The method of claim 1 , wherein the first, second, and third counters are implemented on respective first, second and third TCAMs.

6. The method of claim 1 , wherein the first, second, and third counters are implemented on a single TCAM.

7. The method of claim 1 , wherein the step of incrementing a third counter comprises incrementing the third counter regardless of the marked color.

8. The method of claim 1 , further comprising ascertaining if there is a TCAM entry for the identifier; ascertaining, responsive to there being said TCAM entry, if there are three TCAM counters associated with the entry; and configuring, responsive to there being fewer than three such TCAM counters, one or more TCAM counters associated with the entry so there are a total of at least three TCAM counters associated with the entry.

9. The method of claim 8 , wherein configuring comprises configuring the one or more counters such that two of the at least three counters are configured on a first TCAM and a third of the at least three counters is configured on a second TCAM.

10. The method of claim 9 wherein configuring said policy in the flow policy storage comprises configuring said policy on either the first or second TCAM.

11. The method of claim 1 , further comprising: responsive to the flow not matching a srTCM flow policy, configuring said policy in a flow policy storage.